1. Field of the Invention
The present invention relates to a tuyere of a blast furnace for making pig iron, and, in particular, to a water-cooled tuyere of a blast furnace for blowing in pulverized coal.
2. Description of the Prior Arts
Recently, to improve productivity of a blast furnace or to make use of furnace top gas as a material for the synthetic chemical industry, various methods of allowing oxygen to be a major constituent of blast gas have been proposed. Japanese Examined patent publication (KOKOKU) No. 32323/77 discloses blowing in concentrated oxygen and gas reformed from furnace top gas. Another method is disclosed in a Japanese patent application laid open (KOKAI) No. 159104/85 wherein through tuyeres, oxygen and H.sub.2 O or CO.sub.2 as tuyere nose flame temperature control agents are blown in and, at the same time, gas which is free from N.sub.2 is blown in through an intermediate level of a blast furnace. In the specification of this Japanese patent application, blow-in of pulverized coal of 100 kg/ton pig molten iron is disclosed, but there is no description of a method for blowing in pulverized coal. Furthermore, in a prior art blast furnace, pulverized coal is injected together with an appropriate carrier gas through hole openings of tuyeres, but the prior art method has difficulty in burning significant amounts of the pulverized coal.